Torque sensors known in the art rely on a magnetoelastic element attached to a component to sense torsion forces in the component. Deformation in the component caused by applied torque deforms the magnetoelastic element, resulting in a magnetic field that is proportional to the applied torque. A magnetometer disposed near the element detects the magnitude and polarity of the magnetic field, which indicates the magnitude and polarity of the applied torque.
Magnetoelastic elements applied to cylindrical shafts are normally cylindrical as well to accurately reflect any changes in the shaft caused by applied torque. The magnetic field generated by a cylindrical element, however, tends to have a sharp spike at the measurement location, requiring precise alignment between the magnetometer and the element to obtain accurate readings of the spike. Normal mechanical mounting tolerances may cause slight axial and/or radial misalignments, however, making the magnetometer sensitive to the relative position of the element and the magnetometer. More particularly, if the magnetometer and/or element position shifts slightly and measures the magnetic field in an area other than the spike, the magnetometer will falsely indicate a change in the applied torque. Tighter tolerances may help reduce misreadings, but can be difficult to maintain during normal operations.
There is a desire for a torque sensor that is less sensitive to the physical alignment between the element and the magnetometer.